Jaw hinge axis locator

ABSTRACT

A jaw hinge axis locator having a stiff wire frame with two curving segments which extend around the sides of a dental patient&#39;&#39;s face from the handle of a mouthpiece mounted on his lower jaw, and a pair of dead soft wires connected to the outer ends of the curving segments of the frame. The dead soft wires terminate near the ends of the patient&#39;&#39;s jaw hinge axis, and have flat squares of clear plastic, with grid markings, attached to their outer extremities. Each plastic square has an easily observable center of rotation which pinpoints the patient&#39;&#39;s jaw hinge axis when he moves his lower jaw.

I United States Patent 1 1 3,577,855

[72] Inventor Lloyd Baum 3.078.584 2/1963 Cohn 33/l74(D) 7 pp NO gst gLoma Linda 92354 Primary Examiner-Samuel S. Matthews Filed Mar. 17, 1969Attorney-John H. Crowe [4 Patented May 11, 1971 4 AW HINGE AXIS LOCAT R[5 1 Claims 4 Drawin 0 ABSTRACT: A aw hinge axis locator having a stiffwire trame g g t with two curving segments which extend around the sidesof a U.S. dental aticnt's face from [he handlc of a mouthpigce 32/20mounted on his lower jaw, and a pair of dead soft wires con- [5 1 III. inected to the outer ends of the curving egments of the frame [50] Fieldof Smrch ..33/l74 (D); The dead ft wires terminate near the d f h i m'32/20 jaw hinge axis, and have flat squares of clear plastic, with gridmarkings. attached to their outer extremities; Each plastic [56]Reiemnces (med square has an easily observable center of rotation whichpin- UNITED STATES PATENTS points the patients jaw hinge axis when hemoves his lower 3,056,210 10/1962 DePietro 33/174(D) jaw.

pma- May 11,1911 V 3,577,855

INVENTOR. LL 0 0 BAuM BY Mas-M Asa/7',

JAW runes AXIS LQCATOR BACKGROUND OF THE INVENTION This inventionrelates generally to dental apparatus, and more particularly to animproved device for use in locating the hinge axes of dental patientslower jaws.

In restorative dental work, it is sometimes necessary to accuratelylocate the temporomandibular joint, or jaw hinge, axis of a dentalpatient. Devices of various types have heretofore been proposed for usein locating this axis, and while many have served their purpose fairlyeffectively, none of which I am aware has been free of certain inherentshortcomings. Such devices have invariably been constructed alongconventional face bow lines, characterized by the presence of a crossbarcarrying a bite-supporting member and two side arms. Each side armsupports an indicator member at its rear end which moves in such a wayas to indicate, in some fashion, the location of the patients jaw hingeaxis under the stimulating influence of his jaw movements (generallyfollowing a series of positional adjustments coordinated with the jawmovements).

While some of the prior art jaw hinge axis locators have been lighter inweight, and less complex, than others, even the lightest and simplest ofthese devices have been somewhat bulky and cumbersome, leaving much tobe desired from patient comfort and ease and facility of usestandpoints. The heavier and more complex of the devices have generallybeen more difficult to use than their lighter counterparts, primarilybecause of their inclusion of a greater number of adjustable parts, andhave, additionally, made things rather uncomfortable for a great manydental patients because of their weight and the relatively long periodsof time they must be held by the patients while their parts are beingadjusted for jaw hinge axis-locating purposes. Furthermore, such devicesare, as a result of their complexity of parts and the precision withwhich those parts must be made, rather expensive to manufacture.

Regardless of its weight, bulk or complexity of parts, however, each ofthe prior art jaw hinge axis-locating devices of which l amawarerequires coarse and fine adjustment of its functioning mechanism afterbeing positioned for use on a dental patient. in certain of the morecomplex devices, such adjustment involves numerous steps, and is of arather timeconsuming and tedious nature. In many cases, the adjustableparts are so interdependent that execution of certain of the necessarysteps of adjustment requires a high degree of expertise to avoid thedisturbance of settings obtained in previously executed steps of theprocedure. While the lighter, less complex of the prior art jaw hingeaxis locators have sometimes required less than their more complexcounterparts in the way of adjustment, every such locator of which l amaware requires both coarse and fine adjustment of some sort, generallyincluding such steps as screw-tightening, anntelescoping,pointer-bending, etc., steps, for satisfactory operation. The necessityfor such adjustment is doubly disadvantageous in increasing thedifficulty of use of the prior art locators and adding to the dentalpatients discomfort because of the time-consuming nature of theadjusting manipulations.

Besides their above-noted bulk and weight, difficulty of use, andpatient discomfort shortcomings, present to a greater or lesser degreein each, the aforesaid jaw hinge axis locators are characterized by yetanother shortcoming, namely, lack of any self-contained means for aquick doublecheck of the accuracy of their findings. While it is, ofcourse, possible to back any such instrument away from a final positionof adjustment, and repeat all or part of the just-completed jaw hingeaxis-locating procedure, this is time consuming and, moreover, does notrepresent a doublecheck approach to the problem. Finally, most of theprior art jaw hinge axis locators employ a pointer, or pointed stylus,as the aforesaid indicator member, sometimes used in conjunction with aflag," or plate covered with graph paper, which is placed against thepatient's skin in the area of his jaw hinge axis. The point of thestylus is adjusted until it spins in place as the patient moves hislower jaw,

whereat it is considered to be in line with the patients jaw hinge axis.Determination of the spinning position of the stylus point is made byeye, and therefore depends upon the observers perceptive ability andjudgment for its accuracy.

The stylus-manipulating procedures for locating jaw hinge axes describedabove are often incapable of producing accurate results because ofinherent shortcomings of the necessary procedural steps, and/or theinherent necessity for human judgment in areas where such judgmentisreadily susceptible of error. Thus, where a flag is employed inconjunction with a stylus for determining the location of a dentalpatients jaw hinge axis, the position of the axis is actually spotted onthe outer surface of the flag, where, because of the flags thickness, itis spaced outwardly from the patients skin surface. Strictly speaking,the finding is true only at this location, and it is a common practiceto attempt minimization of the error introduced by the flag thickness topress the flag against the patients skin during the jaw hingeaxis-locating procedure, and remove it after the spin point of theforward end of the stylus has been determined to permit the skin surfaceto resume its natural contours. Tattooing ink is then placed on the endof the stylus, after which the latter is pressed against the skin toform a spot. This technique generally fails to compensate for theabove-noted error, however, because it is almost impossible to hold theflag completely flush against the skin. This is primarily true becauseof the influence of such physical abnormalities as asymmetrical facialcontours, prominence of the malar processes, depressed areas at thecondylar regions, markedly tapering faces, protruding ears, and thelike, which result in the formation of spaces between the-flags andadjacent skin areas or otherwise prevent flush emplacement of the flagagainst such areas. Moreover, the accuracy of transfer of the jawcondyle axis point from the flag surface to the skin may be adverselyaffected by head posture, skin folds, undetected muscular contractionsof the ear or other facial movements capable of causing a change of skinposition over the condylar area.

Whether or not pointed styli are employed in conjunction with flags orplates of the above-described type, error often results in attempts tomark jaw hinge axis locations on patients faces because of misalignmentbetween the styli and the patients jaw condyle axes. Thus, inconventional methods of jaw hinge axis location emplying styli, only theinner ends of the latter are-set for spinning movement, with the resultthat their outer ends almost always move in arcuate paths after theirinner ends have been spin oriented. Assuming that the pointed end ofsuch a stylus is accurately aligned with the patients jaw hinge axis, itwill be apparent that any movement of the stylus toward the patientsface to mark a spot on his skin throws the point of the stylus off ofthe jaw hinge axis to cause inaccurate positioning of that mark.Moreover, mere visual observation of the stylus in motion is hardlycalculated to assure ascertainment of the position at which its innerend spins in place with any great degree of accuracy. This isparticularly true where the stylus is short, or when its outer endwobbles or describes arcuate movements during the jaw hingeaxis-locating procedure. Finally, the slowness of rotation of thestylus, due to the relatively slow movement of the patients lower jaw,coupled with the limited range of his jaw movement, adds to thedifficulty of precisely determining the spinning location of the innerend of the stylus.

SUMMARY OF THE lNVENTlON The jaw hinge axis locator of this invention isa simple, lightweight device of streamlined shape having a minimum ofcooperating parts. in its preferred form the device has a wirelike frameof extremely light weight, adapted to fit rather closely around (but innontouching relationship with) a dental patients face without thecumbersome bulk of the conventional face bow. By virtue of its designand manner of use and functioning, the locator requires virtually nohand manipulation or adjustment of any of its parts beyond an initialcoarse" adjustment of the utmost simplicity. As will be seen, no fine"adjustment of the device is ever necessary, visual observation alonebeing adequate to determine the precise location of a dental patientsjaw hinge axis from the coarse setting of the instrument. The device,moreover, is designed to function in such a way as to permitdoublechecking of its findings with ease and rapidity, and quickcorrection of the latter, where necessary or desirable, to a high degreeof accuracy. Finally, my novel jaw hinge axis locator does not dependupon visual observation of the end of a pointer or stylus, with itsinherent imprecision, for the pinpointing ofjaw hinge axis locations,but utilizes a different, and much more accurate pinpointing techniquefor this purpose.

It will be apparent from the foregoing that my new jaw hinge axislocator is sufficiently different in design, manner of use and manner offunctioning from prior art jaw hinge axis locators, at least in itspreferred form, to avoid all of the abovenoted shortcomings of thelatter. Even in embodiments other than its preferred one, moreover, mynovel locator is so unique in its structure and use capabilities as tobe absent all or most of these shortcomings of the prior art locators.

In its preferred form, my novel jaw hinge axis locator comprises a framehaving a pair of thin, wirelike arm segments (hereinafter referred to asarms) designed for attachment, through an adapter, to the handle of amouthpiece in such fashion as to extend curvingly around the sides of adental patients face when the mouthpiece is secured to his lower jaw inthe below-described manner. The frame is rotatably adjustable in theadapter, so that its arms can be made to angle upwardly from front endpositions near the patients mouth to rear end termination in thevicinity of the jaw hinge axis area either side of his face. Thispositional adjustment of the arm angles, coupled with a simplefore-and-aft adjustment of the arms, hereinafter to be described,comprises the coarse locator adjustment previously referred to.

Each of the arms of the frame of my jaw hinge axis locator is, in turn,made up of two segments, a stiff forward segment, shaped to curve aroundthe forward part of the patients face, and a second segment, constructedof a dead-soft metal or alloy. The second segment of the arm ispreferably of smaller cross section than its forward segment, and servesto extend the arm from the rear end of the latter to the vicinity of thepatients jaw hinge axis, the two segments being joined together for thispurpose in any convenient manner, as, for example, by means of acylindrical connector with a pair of oppositely directed, alignedsockets, sized to receive the ends of the segments, and a pair ofcooperating setscrews adapted to lock the segments in place in thesockets. Fixedly secured to the rear end of each of the second(dead-soft) segments of the arms of the jaw hinge axis locator is asquare plate of a transparent material such as, for example, plexiglass.The plate is marked with crossing lines, which form a grid patternthereon, and is sized to cover the general area of the patients jawhinge axis on one side of his face when the locator is adjusted to itscoarse setting on the patient.

When the locator is positioned as indicated above on a dental patient,and the patient opens and closes his mouth, the square plates on theends of its arms rotate reciprocally about respective center points. Thecenter of rotation of each plate can be easily spotted by the naked eye,with the aid of the grid markings on that plate. This center of rotationcoincides with the patients jaw hinge axis and overlies the position ofthe latter on the patients face. It is an easy matter to spot thisposition on the patients skin, through the rotating plate, after whichthe plate can be moved out of the way, by bending the dead-soft segmentof the locator arm to which it is attached, and the jaw hinge axislocation marked on the patients face in some manner. Repetition of thisprocedure either side of the patients head results in the emplacement ofmarks on his face at the two ends of his jaw hinge axis. If greateraccuracy in locating these marks is desired, the locator can be made toserve in a doublechecking capacity by placing a mark at the center ofrotation of each of the plastic plates, after that center has beenvisually determined in the above-described manner; moving the plate outof the way by bending the deadsoft segment of the arm of the locator towhich it is attached; lightly marking the position of the patients jawhinge axis on his face; moving the plastic plate back over the jaw hingeaxis area of the patients face and aligning the mark on the plate withthat on his skin; and, finally, observing whether the two marks remainin coincidence as the patient opens and closes his mouth. If correctionof the location of the mark on the patient's face is necessary, as aresult of this procedure, it is a simple matter to once again move theplastic plate out of the way, and make the correction. The plate-movingsteps of the doublechecking procedure can be repeated as often as necessary to achieve maximum accuracy, although such repetition is generallynot required for satisfactorily precise results.

It is thus a principal object of the invention to provide an extremelylightweight device, of simplified construction, for the rapiddetermination of a dental patients jaw hinge axis location with minimaldiscomfort to the patient.

It is another object of the invention to provide such a device whichrequires only simplified coarse adjustment, and no fine adjustment, ofits parts when being fitted for use on a dental patient.

It is still another object of the invention to provide such a devicewhich yields inherently accurate results with a minimum of effort on thepart of the operator.

Yet another object of the invention is to provide such a device havingan inherent capability for use in a self-checking capacity.

Other objects, features and advantages of the invention will becomeapparent in the light of subsequent disclosures herein.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of apreferred embodiment of a jaw hinge axis locator in accordance with thisinvention in a fully assembled position of use.

FIG. 2 is a somewhat enlarged front view of the jaw hinge axis locatorpositioned for use on a dental patient, a part of the patient's facebeing depicted in phantom lines.

FIG. 3 is a side view of the jaw hinge axis locator so positioned, thelocator being shown in solid lines in an exaggerated lower position, andin phantom lines in an upper position, of use, and the location of thecenter of rotation of a plate member forming an important part of thelocator being shown by means of an index mark thereon.

FIG. 4 is a slightly enlarged side view of a fragmentary portion of thelocator, showing a length of dead-soft wire forming an end segment of anarm member thereof, and showing additionally a connector joining thedead-soft wire to a stiff segment of the arm, two different positions ofthe length of deadsoft wire being illustrated by solid and phantomlines, respectively, to demonstrate an important functional feature ofthe locator.

DESCRIPTION OF THE PREFERRED EMBODIMENT Considering now the drawing ingreater detail, there is shown generally at 10 a preferred embodiment ofa jaw hinge axis locator in accordance with this invention. Jaw hingeaxis locator 10 comprises a mouthpiece 11, including an impression tray12 of conventional design, and a flat handle 14, having acrescent-shaped end 13 which is fixedly secured to the bottom of theimpression tray by soldering, or equivalently suitable, means, asillustrated in FIG. I, and a flat, elongate, longitudinal segment 15,extending outwardly from said crescent-shaped end, again as illustratedin FIG. 1; a stiff, curving wire 22; an adapter 16 for fastening thestiff, curving wire to handle 14 in the manner illustrated in FIG. I; apair of dead-soft wire segments 24; a pair of connectors 26, for holdingthe ends of the stiff curving wire and the dead-soft wire segmentstogether in the aligned relationship illustrated in the drawing; and apair of transparent plastic plates, or squares, 36, of identical size,fixedly secured to the rearwardly disposed ends of the dead-soft wiresegments by means of a pair of sleeve holders 34, again in the mannerillustrated in FIG. 1. As the drawing shows, each of the plates 36 ismarked with a grid pattern of crossing lines. Although these plates canbe of any suitable size, they are preferably five-eighths inch square.

Adapter 16 is simply a metallic block, having the general form of arectangular parallelpiped, through which run perpendicularly disposedslideways for the handle of mouthpiece 11 and the midsection of stiffwire 22, respectively. The slideway for the handle of the mouthpiece isa T slot 17 running transversely through the lower portion of theadapter, as illustrated in FIG. 2, and sized to receive the mouthpiecehandle in its upper, wider portion, again as illustrated in FIG. 2. Aswill be apparent, the adapter is slidably movable along the handle ofthe mouthpiece, for fore-and-aft adjustment of the position of theconnected curving wire and dead-soft wire segments of the locatorassembly (which parts, as will also be apparent, form a pair ofarms-designated hereinafter as arms 2l-adapted to fit around the sidesof a dental patients face). An illustrative outline of such a face isshown in phantom lines, at 19, on the drawing. Adapter 16 is adjustablealong the handle of mouthpiece 11 with the aid of a pair of setscrews 18mounted in two tapped openings running perpendicularly to the handlethrough the adapter, in the manner illustrated in the drawing. FIG. 3shows one of these setscrews in locking engagement with the mouthpiecehandle.

Running perpendicularly to T-slot 17, at a higher level, through adapter16, is a round bore 23, sized to receive the midsection of stiff wire 22in freely sliding relationship. While stiff wire 22 is, as previouslyindicated, of curving configuration, it has a straight segment in themiddle to permit its sliding interfit with bore 23 of the adapter in theabove-indicated manner. Adapter 16 is provided with a pair of setscrews20, threadedly engageable with a pair of tapped openings so positionedas to permit tightening of the screws against the straight midsection ofstiff wire 22 to lock the latter in place, all as illustrated in thedrawing, particularly FIG. 2. The stiff wire portions of arms 21 arecurved to fit around the sides of a dental patients face, in relativelyclose, but nontouching relationship, when jaw hinge axis locator ispositioned for use on the patient as taught herein.

Each of the dead-soft wire segments 24 of the locator arms 21 is formedof a metallic material of dead-soft character, sub stantially lacking inresiliency and adapted to remain in any position into which it is bentwithout spring-back to its original shape. Such segments may be formedfrom extruded aluminum, gold, soft solder or other metal (pure oralloyed) having the necessary properties of dead softness taught herein.Preferably, the dead-soft wire segments are of smaller cross sectionthan stiff wire 22, to increase their flexibility and make them easierto bend.

Connectors 26 are metallic members of cylindrical shape having aligned,counterbored recesses in their ends sized to matingly receive therearwardly extending ends of stiff wire 22 and the forwardly disposedends of dead-soft wire segments 24, respectively, in the manner bestillustrated in FIG. 4. A pair of setscrews 32 are mounted in a pair oftapped openings running radially into each of the connectors 26sufficiently far to permit the screws to lock the stiff wire anddead-soft wire segments in place in the connectors, again as bestillustrated in FIG. 4.

Press fitted onto the rearwardly disposed ends of each of the dead-softwire segments 24 is a sleeve holder 34. Each of sleeve holders 34 is ofgenerally tubular shape and pushed partway onto a separate one of thedead-soft wire segments (in the above-indicated press-fit relationship)to leave a rearwardly disposed portion of its hollow centerunobstructed. Running from the rearwardly disposed end of the sleeveholder, for substantially the length of the unobstructed portion of itshollow center, is a straight slot 35, adapted to receive one of theplates 36 and hold it sufficiently tightly to provide adequate supportfor the latter during usage of the locator.

As will now be apparent, each of the dead-soft wire segments 24 isrotatable within its mating recess, or socket, in

connector 26, and can be secured therein at varying angles of rotation,by means of the rearwardly disposed pair of setscrews 32, to permitgenerally parallel positioning of plates 36 with respect to the sides ofa dental patients face. The resulting parallelism between the plates andthe, patients face permits a dentist, or dental technician, to looksquarely at either side of the patients head through one of thetransparent plastic plates and obtain an undistorted view of the surfaceof the patients skin, for accurate pinpointing of the location of hisjaw hinge axis from a sight point on the plate determined in accordancewith the below-described axis-locating procedure.

To prepare jaw hinge axis locator 10 for use, the impression tray 12 ofmouthpiece 11 is first filled with a suitable impression material, suchas alginate, and then fitted over the lower teeth of the patient as thelatter holds his mouth open, in a position generally as indicated(although in exaggerated formfor better illustrative effect) in solidlines in FIG. 3. The patient is instructed to close on the tray andthereby bring it into the phantom line position shown in FIG. 3,whereupon the impression material will, upon setting, firmly anchor thetray to his lower jaw and permit it to move coactively therewith. Theanchoring of mouthpiece 11 to the patients jaw in this fashion can becarried out with or without attachment of adapter 16 and arms 21 to themouthpiece handle. In any event, the maximum locator adjustmentgenerally necessary, after mouthpiece 11 has been mounted on thepatients jaw, is a simple sliding adjustment of adapter 16 along handle14 of the mouthpiece (for proper fore-and-aft positioning of arms 21relative to the patients face), and rotational manipulation of stiffwire 22 in bore 23 of the adapter, to assure proper positioning ofplates 36 over the jaw hinge axis areas either side of the patientsface. If any additional adjustment is required, as, for example, tocompensate for misalignment of the sides of a patients face, it is asimple matter to bend one, or both, of the soft wire segments of thearms 21 to the extent necessary for the purpose. This adjustingcapability permits use of the locator on practically anyone (regardlessof the shape of his face) with essentially the same ease and lack ofdifficulty, and constitutes an important feature of my invention.

After jaw hinge axis locator 10 has been fitted to the head of a dentalpatient in the above-described manner, it is ready for service. All thatis now necessary is for the patient to engage in rotational jawmovement, usually under the manipulation of a dentist. While thismovement is occurring, the dentist looks through each of the plasticplates 36 to the underlying skin of the patient. The patients jawmovement causes plates 36 to rotate reciprocally about a dead centerpoint, or center of rotation, as the point will hereinafter be referredto. This center of rotation is in alignment with the patients jaw hingeaxis, and the observer can easily spot it (with the aid of the gridmarkings on the plate) then pinpoint the corresponding location of thejaw hinge axis on the patients face. Once such pinpointing of the axishas been accomplished, it is a simple matter to move the overlying plate36 out of the way, by bending its supporting dead-soft wire segment inthe previously indicated manner, and mark its location on the patientsskin. This procedure is followed on each side of the patients face fordelineation of each end of his jaw hinge axis. Doublechecking of theaccuracy of the jaw hinge axis location determination either side of thepatients face can be accomplished by placing a mark at the center ofrotation of the corresponding plate 36, such a mark being shown at 38 onFIG. 3, before moving that plate out of the way to mark the patientsskin, then proceeding in accordance with the doublechecking procedurepreviously described herein.

From the foregoing description, considered conjunctively with thedrawing, it will be evident that jaw hinge axis locator 10 is, by virtueof its extreme lightness of weight, absence of structural complexity,and simplicity of use and functioning, operable in such a way as toachieve all of the above-noted advantages over presently known jaw hingeaxis locators. Thus,

the lack of structural complexity of the locator makes for rapid fittingof the device to a dental patients face, and determination of the jawhinge axis location with a minimum of time and effort. The lightness ofweight of the locator contributes greatly to a minimization of patientdiscomfort during utilization of the instrument, by comparison with thediscomfort accompanying usage of the heavy and bulky jaw hinge axislocators of more conventional types. Because of its unique design andmanner of functioning, the device yields results of a high degree ofaccuracy and has an inherent selfcorrecting capability to permitupgrading of those results, where possible, to an even higher degree ofaccuracy. A particular feature of locator 10, not heretofore mentionedbut perhaps evident from the foregoing description, is that it can beused with a conventional alginate impression tray, rather than requiringa custom-made clutch adapter. The advantages of increased versatilityand decreased manufacturing expense attributable to this utilization ofa standard part in the locator assembly of my invention will be readilyapparent to those skilled in the dental arts in the light of presentteachings.

The present invention has been described in considerable detail in orderto comply with legal requirements for a full public disclosure of atleast one of its forms. Such detailed disclosure is not, however,intended to unduly limit the scope of the patent monopoly sought to begranted. Accordingly, while my novel jaw hinge axis locator has beenherein illustrated and described in what is considered to be a preferredembodiment, it is emphasized that departures may be made therefromwithin the scope of my invention. Exemplary of such departures arenoncritical variations of the shapes of the component parts of the jawhinge axis locator; the use of substitute, for preferred, materials ofconstruction for the locator parts; the elimination of certainstructural, or other, features of the locator not critically essentialto its proper use and functioning; the addition of useful, butnoncritical, components to the locator; etc.

More specifically illustrative of those modifications of jaw hinge axislocator 10 within the scope of my invention are such changes as thesubstitution of a pair of stiff wire members, extendible from the endsof bore 23 in adapter 16, for stiff curving wire 22; the substitution oflonger connecting elements for connectors 26 (to permit adjustment ofthe length of the locator arms to a greater extent than is possible witharms 21); the substitution of glass, or other suitably clear, plates forclear plastic plates 36; the substitution of plates other than squareones for plates 36; the substitution of equivalently suitable center ofrotation-indexing markings for the grid markings on plates 36; thesubstitution of permanent connecting means between the stiff anddead-soft portions of arms 21 for connectors 26; and other modificationsof similarly noncritical character.

While usage of the jaw hinge axis locator of this invention has beenheretofore discussed in terms of reference to patients with teeth, Iwish to make it clear that the locator is equally applicable for use onpatients who have lost their teeth. In the latter connection, thewirelike frame of the locator can be attached to the lower jaw of anedentulous patient by means of a lower, or mandibular, baseplate andbite rim. More specifically, the lower baseplate can be clamped orsecured to the mandibular edentulous arch of such a patient, after whichthe patients lower jaw can be subjected to rotational movement and hishinge axis located in a manner similar to that described above for thelocation of the jaw hinge axis of a patient having an impression traysecured to his lower teeth.

I wish to emphasize, in final summary, that the scope of my inventionincludes all of its variant forms encompassed by the language of thefollowing claims. In the claims, the term mouthpiece" includes theabove-mentioned baseplate-bite rim-type of mouthpiece apparatus for useon edentulous patients, as well as the impression tray-type of apparatusfor use on patients with teeth.

I claim:

1. Jaw hinge axislocating means comprising:

thin, elongate means, so sized, shaped and securable to the handle of amouthpiece as to extend from said handle partway around at least oneside of a dental patients face to termination near the area of his jawhinge axis, when the mouthpiece is mounted for use on his lower jaw; and

at least one flat, transparent plate member having center of rotationindexing markings thereon;

said thin, elongate means having said fiat, transparent plate memberaffixed at each end near said area of the patients jaw hinge axis insuch fashion as to overlie that area;

at least a portion of said thin, elongate means extending from each endto which said flat, transparent plate member is affixed being ofdead-soft character to permit bending thereof and movement of said plateback and forth between positions of overlie and exposure with respect tosaid patients jaw hinge axis area;

all parts of said jaw hinge axis-locating means serving to permit therapid location of said patients jaw hinge axis either side of his facethrough observation of said flat, transparent plate member as thepatients lower jaw is subjected to rotational movement, and notation,with the aid of said center of rotation-indexing marking thereon, of thecenter of rotation of said plate member, and to permit subsequentmovement of said plate member out of the way and easy marking of thelocation of the appropriate end of the patients jaw hinge axis on hisface.

2. Jaw hinge axis-locating means in accordance with claim 1, in whichsaid thin, elongate means comprises a pair of wirelike arms adapted tocurve from the vicinity of the handle of said mouthpiece around eachside of said patients face in relatively close, but nontouching,proximity thereto, when said locating means is mounted for use on thelower jaw of the patient.

3. Jaw hinge axis-locating means in accordance with claim 2, includingan adapter for connecting said wirelike arms to the handle of saidmouthpiece, said wirelike arms being joined together by means of astraight wire segment of round cross section, integral to both, and saidadapter having a transverse bore, of round cross section, adapted toreceive said straight wire segment, in freely rotatable relationship,and setscrew means for locking the straight wire segment in position inthe bore, whereby angular adjustment of the positions of said armsrelative to said handle is readily achievable.

4. Jaw hinge axis-locating means in accordance with claim 2, in whicheach of said arms has a rigid arcuate segment consisting of a piece ofstiff curving wire, sufficiently long to extend, in a position of use ona dental patient, from the vicinity of the handle of said mouthpiece toa point short of the area of said patients jaw hinge axis on one side ofhis face; a dead-soft segment consisting of a piece of dead-soft wire ofa length sufficient to extend from a point near the rearwardly disposedend of said rigid arcuate segment, when the latter is in theabove-indicated position of use, to termination near the patients jawhinge axis, and a connector having counterbored recesses, serving asreceptive sockets for adjacently disposed ends of the rigid anddead-soft segments of the arm, and cooperating means for locking theadjacently disposed ends of said segments in said counterbored recessesin generally aligned relationship.

5. Jaw hinge axis-locating means in accordance with claim 3, in whicheach of said arms has a rigid, arcuate segment consisting of a piece ofstiff, curving wire, sufficiently long to extend, in a position of useon a dental patient, from said adapter to a point short of the area ofsaid patients jaw hinge axis on one side of his face; a dead-softsegment consisting of a piece of dead-soft wire of a length sufficientto extend from a point near the rearwardly disposed end of said rigid,arcuate segment when the latter is in its above-indicated position ofuse, to termination near said patients jaw hinge axis; and a connectorhaving counterbored recesses, serving as receptive sockets foradjacently disposed ends of the rigid and dead-soft segments of thearms, and cooperating means for locking the adjacently disposed ends ofsaid segments in said counterbored recesses in generally alignedrelationship.

8. Jaw hinge axis-locating means in accordance with claim 1, including,as a structural element, said mouthpiece.

9. Jaw hinge axis-locating means in accordance with claim 5, including,as a structural element, said mouthpiece.

l0. Jaw hinge axis-locating means in accordance with claim 7, including,as a structural element, said mouthpiece.

1. Jaw hinge axis-locating means comprising: thin, elongate means, sosized, shaped and securable to the handle of a mouthpiece as to extendfrom said handle partway around at least one side of a dental patient''sface to termination near the area of his jaw hinge axis, when themouthpiece is mounted for use on his lower jaw; and at least one flat,transparent plate member having center of rotation indexing markingsthereon; said thin, elongate means having said flat, transparent platemember affixed at each end near said area of the patient''s jaw hingeaxis in such fashion as to overlie that area; at least a portion of saidthin, elongate means extending from each end to which said flat,transparent plate member is affixed being of dead-soft character topermit bending thereof and movement of said plate back and forth betweenpositions of overlie and exposure with respect to said patient''s jawhinge axis area; all parts of said jaw hinge axis-locating means servingto permit the rapid location of said patient''s jaw hinge axis eitherside of his face through observation of said flat, transparent platemember as the patient''s lower jaw is subjected to rotational movement,and notation, with the aid of said center of rotation-indexing markingthereon, of the center of rotation of said plate member, and to permitsubsequent movement of said plate member out of the way and easy markingof the location of the appropriate end of the patient''s jaw hinge axison his face.
 2. Jaw hinge axis-locating means in accordance with claim1, in which said thin, elongate means comprises a pair of wirelike armsadapted to curve from the vicinity of the handle of said mouthpiecearound each side of said patient''s face in relatively close, butnontouching, proximity thereto, when said locating means is mounted foruse on the lower jaw of the patient.
 3. Jaw hinge axis-locating means inaccordance with claim 2, including an adapter for connecting saidwirelike arms to the handle of said mouthpiece, said wirelike arms beingjoined together by means of a straight wire segment of round crosssection, integral to both, and said adapter having a transverse bore, ofround cross section, adapted to receive said straight wire segment, infreely rotatable relationship, and setscrew means for locking thestraight wire segment in position in the bore, whereby angularadjustment of the positions of said arms relative to said handle isreadily achievable.
 4. Jaw hinge axis-locating means in accordance withclaim 2, in which each of said arms has a rigid arcuate segmentconsisting of a piece of stiff curving wire, sufficiently long toextend, in a position of use on a dental patient, from the vicinity ofthe handle of said mouthpiece to a point short of the area of saidpatient''s jaw hinge axis on one side of his face; a dead-soft segmentconsisting of a piece of dead-soft wire of a length sufficient to extendfrom a point near the rearwardly disposed end of said rigid arcuatesegment, when the latter is in the above-indicated position of use, totermination near the patient''s jaw hinge axis, and a connector havingcounterbored recesses, serving as receptive sockets for adjacentlydisposed ends of the rigid and dead-soft segments of the arm, andcooperating means for locking the adjacently disposed ends of saidsegments in said counterbored recesses in generally alignedrelationship.
 5. Jaw hinge axis-locating means in accordance with claim3, in which each of said arms has a rigid, arcuate segment consisting ofa piece of stiff, curving wire, sufficiently long to extend, in aposition of use on a dental patient, from said adapter to a point shortof the area of said patient''s jaw hinge axis on one side of his face; adead-soft segment consisting of a piece of dead-soft wire of a lengthsufficient to extend from a point near the rearwardly disposed end ofsaid rigid, arcuate segment when the latter is in its above-indicatedposition of use, to termination near said patient''s jaw hinge axis; anda connector having counterbored recesses, serving as receptive socketsfor adjacently disposed ends of the rigid and dead-soft segments of thearms, and cooperating means for locking the adjacently disposed ends ofsaid segments in said counterbored recesses in generally alignedrelationship.
 6. Jaw hinge axis-locating means in accordance with claim4, in which the center of rotation-indexing markings on the flat,transparent plate members affixed to each of said arms consist of squaregrid markings.
 7. Jaw hinge axis-locating means in accordance with claim5, in which the center of rotation-indexing markings on the flat,transparent plate member affixed to each of said arms consist of squaregrid markings.
 8. Jaw hinge axis-locating means in accordance with claim1, including, as a structural element, said mouthpiece.
 9. Jaw hingeaxis-locating means in accordance with claim 5, including, as astructural eLement, said mouthpiece.
 10. Jaw hinge axis-locating meansin accordance with claim 7, including, as a structural element, saidmouthpiece.